How to Build a Stepper Motor Controller

For precise control of a motor, you can't just hook it up to a power source and let it run. You need exact position, speed and control. You might want to make a robot or turn your webcam using your computer. You might want to control the speed of your motor. Maybe you want to synchronize a couple of motors. Better angle resolution allows fine control of the location on the motor and less "jerky" motion. But how do you control such a beast? This article will show you how to make a stepper motor controller using your PC and an old printer cable called a DB-25.

Things You'll Need

• PC or other computer with a plug
• Stepper motor (unipolar)
• Old printer DB-25 cable
• Needle-nosed pliers
• Wire

Instructions

1. Hook up your DB-25 cable to your old computer. This is the cable that you probably used for your printer before the year 2005. It's called a DB-25 because it has 25 little pins sticking out of the end that used to go into your printer. Don't forget that the stepper motor you use has to be unipolar for this set of plans.

2. Solder all of the parts together, taking care not to damage the parts as they heat up. Heat the parts only as much as you need to for only as long as you need to. You may wish to hold the part with a pair of needle-nosed pliers between the heat and the body of the electronic part for added heat dissipation.

3. Download free software to make your motor work (see Resources below) so that your computer has what it needs. Stepper motor controllers control the turn position by changing the magnetic fields of the electromagnets in a precise way controlled by you. If the electromagnets were 90 degrees apart and labeled according to locations relative to a clock, they would be individually placed at 12, 3, 6 and 9 o'clock. If only the 3 o'clock position were attracting, then the motor would move to that location. The way you set up the pulses of electricity (or stepping) can change the speed and torque of the motor. Do this using the free software.

4. Put the parts together. A soldering iron heats up a chisel-shaped tip to melt solder (usually a mix of metals including a little lead). Insert electronic parts that are then soldered to the location of the metal that cools and hardens. The electricity is left with a well-defined path to travel. Insulate all of the parts so they don't short out.

Tips & Warnings

• Make sure that you don't burn, electrocute or get caught in a motor. Make sure that you research each process carefully before doing them. Whenever possible, do these steps only under the supervision of an expert.

Resources

• A great site on stepper motor basics
• How stepper motors work
• Do-it-yourself plans for a stepper motor controller
• Software for the stepper motor controller
• Decoding schematic diagrams